The present invention relates to an apparatus for sampling a liquid conveyed in a plurality of tubes.
More specifically, the present invention relates to a sampling apparatus forming part of a system for locating a break in a jacket for a reactor and in particular for a liquid sodium-cooled reactor. In such reactors the sealing of the jacket surrounding the fuel elements of the assemblies forming the core is permanently controlled by regularly sampling the cooling liquid from each of the fuel assemblies. For this purpose pipes issue above each of the fuel assemblies. Sampling is carried out by means of a selector which on the one hand permanently samples a mixture of the fluid from all the fuel assemblies, and on the other hand successively takes a sample from each of the tubes.
Numerous different selectors are known. Depending on the particular known construction, they have a base plate into which are welded the ends of the sampling tubes connected to each fuel assembly. In a first construction, these pipes are arranged in accordance with three concentric rings. A suction device having three sampling orifices disposed in accordance with three 120.degree. branches moves in front of the tubes, each orifice permitting samples to be taken from the tubes of one ring. These three samples issue into a mixing box where a secondary selector successively samples one of the three.
Such an apparatus is acceptable in the case where the nuclear reactor only has a relatively limited number of fuel assemblies, that is to say when the selector only has a limited number of sampling tubes. However, such a system could only be used on a more powerful reactor by increasing the number of independent selection devices which necessarily leads to an increase in costs and to an increase in the overall dimensions of such installations placed in the sealing cover of the reactor core whose size is conditioned by the volume of the instrumentation which it must contain.
Selectors are also known in which the tube plate has sampling orifices disposed on a single circle which is concentric to the selector axis. The suction device then passes successively in front of each orifice of the tube plate. Obviously the disadvantage mentioned hereinbefore does not occur; however, for a given enclosure size the number of tubes is necessarily very small.